I have a 1998 xj 4.0 that had a leaking rad but never overheated, always stayed in the 190's. The other day I changed the rad with a brand new one and yesterday the temp gauge was reading 210-215 on the way home and I noticed that the electric fan doesn't seem to kick on. I hard wired the fan to the battery and it works. Any ideas? Could it be a temp sending unit? Thanks

 

if everything worked before the rad swap I'd be looking at plug connections and wiring first.

 

210 to 215 isn't overheating, 240 to 245 or more is. And everything I've ever heard is the XJ is supposed to operate right at 210, that's why the gauge is top dead center at 210, so its easier to read. Mine has NEVER varied from 210 unless it goes a HAIR above when crawling in super hot traffic, towing or before dumping the coolant for new stuff. The electric fan only kicks on with some settings, so its quite possible it wasn't supposed to kick on.

 

Electric fan doesn't kick on till about 218, or if you have the A/C on. One of the best mods I've done was a override switch so I could turn the fan on whenever I wanted.

 

Did you burp it?

 

First step to any suspected overheating is to verify. Don't want to be chasing a ghost.

Get an infrared point and shoot thermometer (inexpensive and everybody should have one) and point it directly at the thermostat housing of a hot engine. Then you'll know for sure.

If what you measure differs from what you are seeing on the dash gauge, start with replacing the coolant temperature sensor, located on the thermostat housing of your 98XJ.

Electric fan should kick in at around 218 degrees, AND it will cycle when you are in defrost or air conditioning mode.

 

210-215 is not over heating. My 98 runs between 210-214 depending what the ambient temp is. 210 is normal operating temp.

 

I realize that a lot of jeeps run 210-215 but mine always ran 190-195 so when I change the rad and nothing else and it jumps up 10 degrees or more when in traffic then I start to wonder what up?

 

Sounds like your fan clutch was on its last legs and when you disturbed it you pretty much killed it.

That or you didn't put the shroud back.

 

A "all of the sudden" 15-25 degree increase does seem odd after only installing a new rad. My guess is your ambient temps are still cool/cold so 190-195 operating temp seems perfectly normal (not 210-215) presuming a 195 stat is installed and functioning correctly.
Backtrack/review your repairs and do what tjwalker and salad said.

 

Burp your cooling system. Park it with the front end elecated and run it with the rad cap open (16lb cap), and fill the rad until the fluid stops bubbling. That's the easiest way. As several people have said, 210 isn't overheating. you may have an air bubble blocking some tubes, though.

 

Maybe the OP should have said "running hotter" instead of "overheating". The bottom line is, for some reason his usual temp is displaying 15-25 degrees higher after replacing the rad. Hopefully the OP has checked the coolant level in both the rad and bottle after several heat/cool cycles. The rad should be full to the top hot or cold. The coolant level in the bottle should rise a little (hot motor) and fall a little (cold motor).

 

Dont fix it if aint broke comes to mind here..

 

Since the OP is saying something has changed, he may need to start looking at why before it does break.................as salad suggested.

 

It is not necessary to tilt '91+ open systems to burp. They self burp when filled as described above by djb383.